Safety for firing mechanisms for cannon using separate loading ammunition



NOV. 1950 w. SUMMERBELL ETAL SAFETY FOR FIRING MECHANISMS FOR CANNONUSING SEPARATE LOADING AMMUNITION Original Filed July 10, 1945 PatentedNov. 28, 1950 SAFETY FOR} FIRING MECHANISMS FOR. ("JANNON' USINGSEPARATE LOADING AMMUNITION William Summerbell, Washington, D. 0., LouisJ. Rhein, Aberdeen, Md., and Owen D. Hoopes,

Watervliet, N; Y.; Edith May Summerbell executrix of said WilliamSummerbell, de-

ceased.

Original application July 10, 1945. Serial No. 604,286. Divided and thisapplication February 16, 1949, Serial No. 76,742

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) 4 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to us ofany royalty thereon.

This application is a division of our copending application, SerialNumber 604,286, filed July 10, 1945 now Patent Number 2,504,162, andrelates to a head-space safety for use in the firing mechanism of largecalibre guns and howitzers.

It is the principal object of the invention to provide a safety devicein connection with a firing mechanism wherein the extractor of theprimer cartridge cannot be moved forward to fully seated position whenthe firing lock housing is not screwed fully home, on the obturatorspindle.

A further object is to provide a mechanism wherein the operation ofscrewing the firing lock housing fully onto the obturator spindle,automatically releases the primer cartridge extractor for full forwardmovement into firing position.

In short, the principal object is to provide a safety mechanism by whichfiring of the gun is positively prevented unless and until the mechanismis fully seated in gas-tight relation with the obturator spindle.

Other objects and advantages will become apparent after a study of thefollowing disclosure.

The invention is intended more particularly for use in cannon ofrelatively large calibre such as the Armys 8-inch, 155 mm., and 240 mm.guns and howitzers. In these cannon the projectile and propellant areseparately loaded. Ignition of the charge is effected by a firingmechanism screwed onto an obturator spindle rigidly united with thebreechand having a central flash passage leading therethrough to thebreech chamber whenthe breech is closed. Firing of the cannon is theneffected by the detonation of a primer cartridge confined in the passagein the obturator spindle plug, in alignment with and in communicationwith, the obturator spindle passage. Since this passage is in directcommunication with the breech chamber and is subjected to the fullpressure engendered by ignition of the propellent therein, it is highlyimportant that the firing mechanism be fully seated and in gas tightrelation with the obturator spindle before a round is fired.

The description of the constructionof the firing lock, its operation andits relation to the breech of the cannon, are all fully detailed anddescribed in the parent application aforesaid and hence need not be hererepeated.

In the drawings.

Fig. 1 is a vertical axial cross section through the rear end of theobturator spindle, spindle plug, extractor and safety.

Fig. 2 is a vertical section taken in a plane identified by the line 22of Fig. 1,

Fig. 3 is an exploded perspective view of the housing, safety plunger,plunger spring and extractor, and

Fig. 4 is a perspective view to an enlarged scale, of the safety orplunger.

The model illustrated is for a gun having a breech ring with interruptedthreads, a breechblock carrier hinged to the breech ring on an axiswhich is normal to the bore axis of the gun, and a breechblock pivotedin the aforesaid carrier upon an axis which is substantially coincidentwith the bore axis of the barrel when the breech is closed, whereby thebreechblock may be locked in the breech ring by means of the usualinterrupted threads and a partial turn of the breechblock.

Thus numeral l identifies a portion of the aforesaid breech carrierhaving a central bore 2 and a counterbore 3 opening through the rearface of the carrier. The rear end of obturator spindle 4 has a rotatablesliding fit in bore 2. A firing lock housing 5 has a first or rear,generally cylindrical portion 6 slidably fitting counterbore 3 and areduced forward extension 1. This extension has an internally threadedbore 9 and an outer diameter sufficiently less than the diameter ofcounterbore 3 to provide an annular chamber accommodating spring 8. Thethreads of bore 9 engage those upon the rear end of spindle 4 as will beobvious from inspection of Fig. 1. Spring 8 exertsa force at one endagainst the shoulder between portions 6 and l and at the other endagainst the shoulder between bores 2 and S, to thereby urge the spindle4 and housing 5 rearwardly.

' The rear end of spindle 4 has a threaded counterbore l0 concentric ofbore or flash passage i5 and into which the reduced forward end I I ofspindle plug I2 is threaded. Spindle plug l2 has an enlarged cylindricalportion 93 rearwardly of "the top of bore l5.

its reduced end II, and a rear portion M of reduced diameter.

As clearly shown upon Fig. 1, when plug 12 is screwed home, its forwardend is in gastight relation with a shoulder formed between counterbore Iand bore I of spindle 4. Tight sealing relation is assured by a washerl6.

Housing 5 has a reduced bore rearwardly of threaded bore 9 to fitportion [3 of spindle plug I2 and is again reduced to form a bore itopening through its rearward face to accommodate rear portion M of plug12. The portion I4 is of substantially smaller diameter than bore I6 sothat extractor H has a smooth fit between them.

Housing 5 is provided with a smooth radial bore l8, which at its innerend, opens into bore IS. A safety or plunger i9 has a fit within bore l8and a reduced inner end 22 adapter to project into bore [6 under certainconditions subsequently explained. The safety I9 is urged into radiallyinward or looking position by a coil spring 25 acting between the bottomof a bore in the safety and a plug 2! threaded into the enlarged outwardend of bore 18. It will be noted from Fig. 4 that the main cylindricalportion of safety [9 and its reduced inner end 22, are joined by asmooth, frusto-conical cam surface 23 for a purpose presently described.

Spindle plug l2 has a central axial bore to accommodate a primercartridge C whose head has a rim seating on the complementary rimsurface of extractor l1 and is thus adapted to be withdrawn from thespindle plug bore by withdrawal of the extractor. The extractor isoperated by a firing lock 24 guided for vertical movement on housing 5by downwardly and rearwardly extending ribs 25 and 26 formed on theconfronting walls of a diametral channel 21 opening through the rearface of housing 5. Lock 24 has cam grooves, not shown, in which fitoppositely disposed lugs 28 and 29 on extractor I1. Thus, as the firinlock and its firing pin 35 are moved downwardly from the closed orfiring position shown upon Fig. l, the extractor is cammed out of thefully seated position shown to withdraw the cartridge C.

From Figs. 1 and 2 it will be noted that the extractor has a pad 3|.This pad fits within a slot or keyway formed in housing 5 in and alongThe arrangement limits the motion of the extractor to axial translation.The parts are so dimensioned and related that, when safety 19 iselevated to the position shown in Fig. l, the pad 3| may slide smoothlybeneath the reduced end 22. However, when safety I9 is allowed todescend from its position shown, under the urge of spring and withextractor I? in rearward position, end 22 moves into the path of pad 31and prevents the extractor and its primer from movement into fullyseated position.

Prior to use, spindle plug l2 will be screwed fully into the end ofspindle 4 and housin 5 and the parts carried thereby are separate andunconnected with the spindle. Extractor II is in retracted position sothat safety [9 has its end 22 projecting into bore l6, thus making itimpossible to move the extractor and cartridge into firing position.

Housing 5 and its associated parts are placed in operative position onthe gun by screwing extension I onto the rear threaded end of obturatorspindle 4. As the extension is turned home, the rearward corner ofenlarged cylindrical portion l3 of plug [2, engages the frusto-conicalsurface 23 of plunger l9 and forces the latter outwardly against theaction of spring 20. When, and only when, the housing 5 is fully seatedon spindle 4. in the position shown upon Fig. 1, plunger 19 is movedoutwardly to clear bore l6 and the firing pin slide may be then closedto move the extractor and a primer cartridge therein into fully seatedposition.

We have thus provided a safety feature which positively prevents the gunfrom being fired unless and until the firing mechanism is fully seatedon the obturator spindle of the gun. It is our desire and intention toreserve all the modifications of the previously-disclosed preferred formof the invention which fall within the scope of the subjoined claims.

We claim:

1. In a firing mechanism for a gun having a breechblock and an obturatorspindle having a first central axial flash passage leading through thebreechblock thereof, said passage terminating rearwardly in a threadedcounterbore, a spindle plug threaded into said counterbore and having anaxial passage shaped to receive a primer cartridge and forming acontinuation of said flash passage, a housing threadable on said spindleinto fully-seated, gas-tight relation therewith, and safety meanspreventing the full insertion of a primer cartridge in said plug unlessand until said housing is threaded on said spindle into fully-seatedposition thereon.

2. In a firing mechanism for a gun having an obturator spindle, aspindle plug rigidly connected with said spindle and having a chamber toreceive a primer cartridge, a housing axially movable on said spindlefrom an initial to a fully seated position thereon, an extractor for acartridge slidably mounted in said housing for movement with a cartridgeinto said chamber, safety means on said housing spring pressed into thepath of said extractor, and means normally responsive to axial movementof said housing to fully seated position on said spindle to retract saidsafety means out of the path of said extractor.

3. In a firing mechanism for a gun having an obturator spindle, aspindle plug threaded into said spindle and forming a chamber for thereception of a primer cartridge, 2. housing threadable onto said spindlefrom an initial to a fully seated position, thereon, an extractormounted in said housing and movable into final position in synchronismwith movement of a primer cartridge into fully seated position in saidchamber, a plunger mounted for radial movement in said housing, a springurging said plunger to project one end thereof. into the path of saidextractor to prevent movement thereof to said final position, said plugbeing engageable with said plunger to retract the same out of the pathof said extractor only when said housing is threaded into fully seatedposition on said spindle.

4. In a firing mechanism for a gun having an obturator spindle throughthe breach thereof, a spindle plug threadedly engaged with the rear endof said spindle, said plug having a chamber opening rearwardly throughthe end thereof to receive a primer cartridge, a firing lock housingthreadable onto said spindle from an initial position to a finalposition in gas-tight relation therewith, an extractor slidable in saidhousing and engageable with the head of a cartridge to move in a unittherewith as said cartridge moves into said chamber means carried bysaid housing to move said extractor and a cartridge therein as a unitthe path a: said extractor onlywhen said hous- 10 ing is in finalposition on said spindle, whereby said extractor and a cartridge cannotbe moved to firing position until said housing is in said finalposition.

WILLIAM SUMMERBELL.

LOUIS J. RHEIN.

OWEN D. HOOPES.

No references cited.

